use the java.net.URLConnection class to specify the url of the jsp  to
connect. use the url (string) like this
http://xxx:9999/yyyy/zzz.jsp?username=tf.getText()&paswd=tf.getText()

where
xxx is the server  name
yyy is the folder address in which the jsp is
& tf's are the textfields which was used to enter the data/

use the Button to trigger the connection.

Networking by o'reilly publication has an example of the similar nature.
if there is still a problem mail me back. i will send  you a samll example of
the same.